Engine



Oct. 14-, 1947. \A. R. EARNYSHAW I 2,428,791

ENGINE v Filed Sept. 21, 1945. s sheets-sheet 1 I INVENTOR.

I L ALVIN R. EARNSHAW 2 BY FIG. I M-%* ATTORNEYS ENGINE A, RfEiA-RNSHAWFiIed Se t ZL, 1945 3- Sheets-Sheet 2 VINUVENTOR. ALVIN R. EARNSHAW ATORNEYS Patented Oct. 14, 1947 UNITED STATES PATENT OFFICE ENGINE AlvinR. Earnshaw, O ildale, Calif.

Application September 21, 1945, Serial No. 617,819

An object of my invention is to provide an engine of the two-cycle typewhich has two intake valves and two exhaust valves with mechanicalcontrol for all of the valves so that the intakevalves will alternatewith each other in permitting gas to be drawn into the engine, and theexhaust valves will alternate with each other to permit the burnt gasesto exhaust from the engine. By this. I mean that during one intakestroke, one intake valvewill open and during the following intake strokethe other intake valve will open. In like manner, during one exhauststroke, one exhaust valve will open and during the next exhaust stroke,the other exhaust valve will open.

Anarrangementof thiskindpermits the engine shaft to rotate at a highspeed and the intake and exhaust valves to operate at half the speed.There will therefore be less likelihood for the valves to float at highengine speed, because more time will be given for each valve to closethan is possible to give where only one intake and one exhaust valve isprovided for each cylinder.

In the drawings I have shown only one cylinder although it is obviousthat as many cylinders as desired may be connected to the same crankshaft.

A further object of my invention is to provide a device of the typedescribed in which the gas passages between the crank case and the topof the cylinder are arranged so that the firing stroke of thepiston willcompress the new charge in the crank caseand then when the pistoncompletes its power stroke, the passages. between the crank case and thecylinder wil1 open and will permit the compressed gas to be forced intothe cylinder top. The piston acts as its own valve for opening andclosing the intake ports in the cylinder wall, The present engine hasbeen designed for use in connection with providing a prime mover for abicycle. This particular adaptation is shown in my co-pendingapplication, Serial No. 645,329, filed Feb. 4, 1946. The engine can beused for any other purpose.

Other objects and advantages will appear in the following specification,and the novel features of the device will be particularly pointed out inthe appended claims.

My invention is illustrated in the accompanying drawings forming a partof this application, in which:

Figure l is a side elevation of the engine;

Figure 2 is a transverse section taken along the line 2-2 of Figure 1;

4 Claims. (Cl. 123-.73)-

2 Figure 3- is-a longitudinal section taken sub;- stantially along theline 33 of FigureZ, and- Figure 4 is a horizontalsection taken along theline-44 of Figure 3.

While I have shown only the preferred forms of my invention, it shouldbe understood that various changes or modifications may be made withinthe scope of the appended claims without departing from the spirit andscope of theinvention.

In carrying out my invention, I provide a crank case indicated generallyat A in Figures 2'and 3. A crank shaft I extends into the crank case andis rotatably supported in a ball bearing 2 or other suitable bearing. Inthe present form of the device the crank shaft I has a pair of sprockets3 and 4 keyed thereto, see Figure 3, and these sprockets are protected.by a casing 5 which is integral with the crank case A. The casing 5 hasa portion extending beyond the sprockets and this portion carriesanother ball bearing 6 or other suitable type of bearing for rotatablysupporting the outer end of the crank shaft I. A pulley I is keyed tothe crank shaft I and this pulley may be connected to any mechanism thatis to be driven, It is obvious that the pulley may be changed for asprocket or a gear if desired. A magneto assembly B is shownmounted atthe outer end of the casing 5 and the crank shaft I extends into thehousing for actuating the ma neto in the usual way.

An engine cylinder C is mounted on the, crank case A and has ring-shapedcoolingfin 8. The engine may be cooled in any manner desired, such as bywater, not shown. A cylinder head D is placed on the top of the cylinderand is secured thereto in the usual manner. The cylinder'head hasradially extending cooling fins 9. The cylinder C has a liner Ill thatextends throughout the length of the bore in the cylinder. Figure 3shows the lower portion of the cylinder as provided with an annularpassage II that communicates with the interior of the crank case Athrough a plurality of openings 5! provided in an inwardly extendingflange 58. The liner ID has an annular row of openings I2 that place theinterior of the cylinder in communication with the annular passage I Iwhen the openings are uncovered by a piston.

Figure 2 shows the crank shaft I carrying a counterweighted crank arm I3and the crank arm has a connecting rod E pivotally secured thereto atI4. The piston F is slidably mounted in the liner Ill and is pivotallyconnected to the crank arm E by the usual wrist pin I 5. A rotation ofintake manifold that in turn communicates with a carburetor 2|. Ifdesired the two intake manifolds l8 and 20 may be combined into one andcommunicate with a single carburetor which may be of the down drafttype.

Figure 2 also shows the intake ports [6 and [1 controlled by intakevalves 22 and 23, .respec: tively. The intake valve 22 is yieldingly'held in closed position by a valve spring 24 while the intake valve 23is yieldingly held in closed position by a valve spring 25. A rocker arm26 bears against the top of the valve stem 21 for the valve 22 while arocker arm 28 bears against the top of the Valve stem 29 of the intake23. The rocker arms 26 and 28 are pivotally mounted at 30 and 3|,respectively.

I show cams 32 and 33 mounted on cam shafts 34 and 35, see Figure 2, andthe cam shafts are rotated by sprockets 39 and 37, which in turn arerotated by a sprocket chain 38 that is passed around these sprockets andaround the sprocket 3, mounted on the crankshaft I. The ratio of thesprocket 3 to the sprockets and 31 is one to two, so that the cam shafts34 and 35 will be rotated at one-half the speed of the crankshaft I. Thehigh points of the earns 32 and 33 are arranged so that during theintake stroke of the piston F, one intake valve will open and during thenext intake stroke of the piston, the other intake valve will open. Thiswill be explained more in detail hereinafter.

I also provide two exhaust Valvesfor the cylinder C and these are shownat 39 and 49 in Figure 2. The exhaust Valve 39 controls the exhaust portwhile the exhaust valve 49 controls the exhaust port 42. Each exhaustvalve 39 and 49 is provided with a valve stem 43 and M, respectively,and valve springs 45 and 46, yieldingly hold the exhaust valve in closedposition. Rocker arms 4! and 18 pivoted at49 and 50 bear against theends of the valve stems 43 and 44 and open the exhaust valves at theproper time.

A cam shaft 5! has a cam 52 with a highpoint 53 that is designed toalternately contact the rocker arms 41 and 53 for every 180 of travel.Should the rocker arms be arranged diiferently, the cam 52 could havetwo high points, one-for each rocker arm. The exhaust valves 39 and 50will be alternately opened and in proper sequence. During the exhaustingof the burnt gas from the cylinder, one exhaust valve 39 will open atone time and the other exhaust valve will open ;for the neXt time.

The cam shaft 5| is shown in Figure 3 as carrying a sprocket 55, whichis keyed thereto. A sprocket chain 55 is passed around the sprocket 55and around the sprocket 4. The ratio of the sprockets 4 and 55 is suchas to cause the cam shaft 5| to rotate at one-half the speed ofthecrankshaft I.

From the foregoing description of the various be readily understood.

Figure 2 shows the exhaust valve 40 open and the piston F ready to startits combined exhaust and compression stroke. reaches bottom dead center,the compressed charge in the crankcase A will pass up through therecesses 51, see Figure 4, that are formed in the flange 58, see Figure2, this flange being integral with the cylinder C and extending inwardlyso as to contact with the portion of the liner In that is disposedadjacent to the lower end of the cylinder. The compressed gas then flowsthrough V the annular passage ll through the openings 2,

and into the combustion chamber of the cylinder. The incoming gas willforce the exhaust gases past the open exhaust valve 40 and into theexhaust pipe 42. The valve 40 is timed so that the cam 52 will movethecam high point 53 past the rocker roller 59 and permit the spring 46 toclose the valve and to swing the rocker arm. The exhaust valve 40 opensat degrees before bottom dead center and closes at 55 to 58 degrees pastbottom dead center.

The closing of the valve 40 traps the compressed gas within the cylinderand the upwardly moving piston compresses the gas still further. InFigure 3 I show two spark plugs 60 and these spark plugs areelectrically connected by a wire 6| to the magneto B. Both spark plugswill be fired by the magneto at the proper time and will ignite thecompressed gas within the cylinder. I have found that when the pivotpoint I4 of the connecting rod E reaches 30 degrees before top deadcenter, the spark plugs should fire. The piston will then move into itspower stroke and the gas ignited by the firing of the dual spark plugswill expand and will drive the piston downwardly.

The intake valve 23 will open after the pivot point M of the connectingrod E reaches 35 degrees past bottom dead center. 'The upwardly movingpiston F will suck the new charge past the open valve 23 and into thecrank case A. The intake valve 23 will close when the pivot point [4reaches about 35 degrees past top dead center. The downward movingpiston on its power stroke will compress the trapped gas within thecrankcase so that this gas will start to flow through the openings l2 assoon as they are uncovered by the piston. It will be seen that theengine works on the two cycle principle and thus far only the exhaustvalve 40 and the intake valve 23 has functioned.

During the next upward movement of the piston F, the exhaust valve 39will open and so will likewise theintake valve 22. The exhaust valve 39will open 65 degrees before bottom dead center of the pivot point I4 isreached and will close when the pivot point is 55 to 58 degrees pastbottom dead center} The intake valve 22 will open 35 degrees afterbottom dead center is passed by the pivot point l4 and will close whenthe pivot point passes 35 degrees beyond top dead-center. Thefdual sparkplugs will fire when the pivot point l4 reaches 30 degrees before topdead center. The intake valve 23 and exhaust valve) will function forone cycle of operation and the intake valve 22 and exhaust valve 39 willfunction for the next cycle of operation. This alternate opening of theintake and'exhaust valves permits the engine to run at a high speed andthe valves to open and close in much the same manner as a four-cycleengine. The engine can deliver afar greater power due to thisarrangement, because the valves will'have sufiicienttime in which toclose and therefore the valves will As soon as the piston have lesstendency to float when the engine reaches a high speed.

I claim:

1. In a two cycle engine, a cylinder having an exhaust opening and inletopenings in the cylinder wall, a crankcase having two inlet openings,means placing the interior of the crankcase in communication with thecylinder inlet openings, a piston reciprocably mounted in the cylinderand, uncovering the cylinder inlet openings when the piston nears thecompletion of its power stroke, a crankshaft operatively connected tothe piston, a controlled exhaust valve for the exhaust opening, an inletvalve for each crankcase inlet opening, and means interconnecting theinlet valves with the crankshaft for causing them to alternately openfor successive intakes during the successive scavenging-compressionstrokes of the piston, whereby each intake valve will open one half thenumber of times it would normally be required to open if only one intakevalve and opening were provided in the crankcase.

2. In a two cycle engine, a crankcase, a cylinder secured to thecrankcase, a liner for the cylinder having inlet openings, said cylinderhaving an annular passage communicating with the openings and having aninwardly extending flange at the end nearest the crankcase, the flangeforming a wall for the annular passage and contacting with the liner foraiding in supporting it, said flange having recesses forming passagewaysbetween the annular passage and the crankcase.

3. In a two cycle engine, a crankcase having two inlet ports, a cylindercarried by the crankcase and having two exhaust ports in the top andinlet openings in its wall communicating with the interior of thecrankcase, a piston reciprocably mounted in the cylinder and uncoveringthe inlet openings as the piston nears the completion of its powerstroke, a crankshaft operatively connected to the piston, inlet andexhaust valves for the inlet and exhaust ports, and meansinterconnecting the inlet and exhaust valves with the crankshaft forcausing the inlet valvesto take turns during successive intake strokesof the piston and the exhaust valves to take turns during successiveexhaust strokes of the piston, whereby the inlet and exhaust valves willopen and close at one-half the speed they would normally require if onlyone inlet and one exhaust valve were provided.

4. In a two cycle engine, a crankcase having inlet ports, a cylindercarried by the crankcase and having two exhaust ports in the top andinlet openings in its wall communicating with the interior of thecrankcase, a piston reciprocably mounted in the cylinder and uncoveringthe inlet openings as the piston nears the completion of its powerstroke, a crankshaft operatively connected to the piston, inlet andexhaust valves for the inlet and exhaust ports, and meansinterconnecting the inlet and exhaust valves with the crankshaft forcausing the inlet valves to take turns during successive intake strokesof the piston and the exhaust valves to take turns during successiveexhaust strokes of the piston, whereby the inlet and exhaust valves willopen and close at one-half the speed they would normally require if onlyone inlet and one exhaust valve were provided, said means comprising apair of sprockets mounted on the crankshaft, rocker arms for the intakeand exhaust valves, cams for actuating the rocker arms, sprocketsconnected to the cams that operate the intake valve rocker arms andbeing connected by a sprocket chain to one of said first-namedsprockets, and a cam for actuating the rocker arms at the exhaust Valvesand being operated by a, sprocket which is connected by a chain to theother side of the first named pair of sprockets.

ALVIN R. EARNSHAW.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,306,198 Stanley June 10, 1919876,880 Johnson Jan, 14, 1908 1,423,365 Smith July 18, 1922 1,445,319Jelbart Feb, 13, 1923 1,289,498 McHarry Dec. 31, 1918 1,366,448 EricksonJan. 25, 1921

